Work vehicles, such as construction, forestry, agricultural or mining work vehicles, typically are propelled across the ground using wheels or endless tracks. Track type work vehicles may include a heavy elastomeric endless track or a steel endless track. An example of an agricultural work vehicle including an elastomeric endless track is the 9030T series tractor which is manufactured and sold by the assignee of the present invention. Examples of construction work vehicles including a steel endless track are the 1050J crawler dozer and 755D crawler loader, each of which are manufactured and sold by the assignee of the present invention.
A crawler type vehicle with a steel endless track as described above typically includes an undercarriage with a track chain which is carried by a plurality of sprockets and rollers. The track chain in turn includes a number of interconnected links, with each link carrying a corresponding shoe that extends crossways to the travel direction of the crawler type vehicle. The links are typically interconnected using a pivoting bushing and pin arrangement at each link joint. Such a link joint may be sealed and lubricated or greased to extend the wear life and prevent foreign matter such as dirt from entering the link joint area.
Link joints which are sealed and lubricated or greased do much to increase the operating life of the track chain. However, it is still possible for the seals to fail at the axial end of the bushing; thus allowing the lubricant to leak out or dirt to enter into the link joint area. When this happens, the operating life of the track chain is shortened considerably.
What is needed in the art is a track chain for a crawler type work vehicle which does not require a sealed or lubricated operating environment, but still has good wear and operating life characteristics.